Automatic fire alarm relay



June 29, 1954 THOMAS 2,682,582

AUTOMATIC FIRE ALARM RELAY Filed Dec. 7, 1951 2 Sheets-Sheet l H 3% 5 Q E E1 Cwzzsnz- Soun 5,3 l 33/ F] a 2.

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J1me 1954 M. K. THOMAS AUTOMATIC FIRE ALARM RELAY Filed Dec. 7. 1951 2 Sheets-Sheet 2 UREA FIG 61 INVENTOR. M; #250 K 7Z/0/m4s, BY

Patented June 29, 1954 UNirEos'rATEs PATENT OFFICE Milfred King Thomas, Birmingham, Ala.

Application December 7, 1951, Serial No. 260,363

a l l 1 This invention relates to improvements in fire alarm systems, and more particularly to an improved automatic fire alarm system operated in response to the presence of a fire in a building or other establishment equipped with the improved system,

A main object of the invention is to provide a novel and improved automatic fire alarm system which may be employed in conjunction with conventional fire alarm apparatus, the improved system being relatively easy to install, being simple in construction, and being reliable in operation. A further object of the invention is to provide an improved automatic fire alarm system adapted for use with conventional fire alarm equipment, the improved system involving inexpensive com- 'ponents, being sturdy in construction, and being easy to maintain in operating condition. y Further objects and advantages of the invention will become apparent from the following description and claim, and from the accompanying drawings, wherein: Figure 1 is a schematic view showing one form of improved fire alarm system according tothe present invention installed in conjunction with a conventional fire alarm switch boX;

Figure 2 is a wiring diagram of the system illustrated in Figure 1;

Figure 3 is an enlarged cross-sectional detail view taken on the line 33 of Figure 1;

Figure 4 is a perspective view illustrating a modification of the solenoid employed in a system according to the present invention installed on another conventional form of fire alarm switch box;

Figure 5 isan enlarged cross-sectional detail view taken on the line 55 of Figure 4;

Figure 6 is a, front elevational View, partly broken away, of another conventional form of fire alarm switch box equipped with improved automatic switch-operating means in accordance with the present invention: 7

Figure '7 is an enlarged cross-sectional detail view taken on the line |1 of Figure 6;

Figure 8 is a schematic diagram showing a further modification of the automatic fire alarm system of the present invention.

Referring to the drawings, and more particularly to Figures 1, 2 and 3, ll designates a conventional fire alarm switch box of the manually operated type, the switch box being provided with a push button switch I2 to which access is ordinarily obtained by breaking a panel of frangible material, such as glass, located in the front cover of the box immediately adjacent to the push but- 1 Claim. (01. ZOO-87) Ill] ton switch l2. The front cover of the box, designated at 13, is formed with an aperture 14 to which is secured a rectangular frame I5. As shown in Figure 1, the frame 15 may be hinged to the front wall l3 at I6, I 6, so that said frame may be swung to open position at times, the frame being maintained closed by any suitable latch means l1. Designated at I8 is a panel of suitable frangible material, such as glass or the like, which is secured in the frame 15, said panel having a central bulged portion [9 located opposite the push button 12. Secured on the frame I 5 is a solenoid comprising a casing 2| containing an annular insulating core 22 on which is wound the coil 23. Designated at 24 is a movable plunger of magnetic material slidably mounted in the core 22, and designated at 25 is a movable rod of nonmagnetic material, such as brass or the like, which is slidably positioned in the annular core '22 between the plunger 2'4 and the inner end aperture 26 of casing 2!. As shown in Figure 3, the plunger 24 is arranged so that when the coil 23 is energized, said plunger will be moved inwardly by magnetic attraction and will drive rod 25 against the centrally bowed portion [9 of the frangible panel l8, causing said panel to be shattered and allowing the movable rod element 25 to strike against the push button switch I2. When the push button [2 is engaged, the associated fire alarm apparatus is energized in the conventional manner.

Designated at 21 are respective thermostatic switches which may be located in strategic portions of the building or other establishment being protected, the respective thermostatic switches '21 being connected in parallel between wires 28 and 29. Wire 29 is connected to one terminal of the coil 23 of the solenoid 20. Wire 28 is connected through one movable pole 30 of a doublepole, single-throw switch 31 to a line wire 32 ing the plunger 24 to be driven inwardly and causing the non-magnetic rod element 25 to be driven through the frangible panel [8 and to cause the switch I 2 to be closed.

Referring now to Figures 4 and 5, the fire alarm box, designated at H, may be of a type wherein the alarm switch is closed by the ro- 3 tation of a shaft 12'. In accordance with the present invention, a solenoid 20 is mounted in the forward portion of the alarm box II with its axis in a horizontal position at right angles to the shaft I2. As shown in Figure 4, the box H may be suitably recessed or otherwise modifled to receive and support the solenoid 20. The solenoid 20' comprises the annular insulating core 22' in which is slidably mounted the magnetic plunger 24 which has secured to its forward portion a rack element 25" formed with rack teethmeshingly engaging the teeth 26 of a gear 21' secured on the end of shaft 12. The

electrical circuit employed with the embodiment l of the invention of Figures 4 and is the same as in the case of Figures 1, 2 and 3, and'when one of the thermostats of the system becomes closed, the solenoid 26 becomes energized and retracts the plunger 24 from its normal position, shown in Figure 5, causing the shaft 12 to be rotated and thereby causing the alarm switch associated with the box ll to be closed.

In the form of the invention shown in Figures 6 and 7,, the alarm box, designated at 36, is of the type having the downwardly movable, horizontally projecting handle element 31 which is arranged to close the. alarm switch, designated at 38, responsive todownward movement of the handle 31 from its normal position. In accordance with the present invention, the handle 3! is provided with an axial bore 39 which receives the laterally projecting end 49 of the solenoid plunger 6!. The plunger 4| is slidably received in the axial bore of the annular insulating member 42 forming part of the solenoid 43, said solenoid being mounted on the wall 44 of the box subadjacent the handle 33' in a vertical position. The energizing circuit for the solenoid 43 is the same as in the two preceding embodiments of the invention, and when one of the thermostats of the system closes, the solenoid 43 becomes energized, causing the plunger 41 to be pulled downwardly,. whereby the handle 3'! is moved downwardly to close the alarm switch 38 and to energize the associated alarm circuits.

In the embodiment shown in Figure 8, a means is provided for energizing the solenoid independently of the thermostats, if so desired. In Figure 8, the current supply wires are shown at 35' and 29, and the solenoidis shown at 40. at 45 is a manuall settable switch of a conventional type which may be set to a closed position, if so desired. The thermostats 2'! are connected in parallel between the line wire29' and a wire 28 which, in turn is connected to one terminal of the solenoid 40' through the manually settable switch 45. The other terminal of the solenoid 40 is connected to the line wire 35 Connected Designated between the first-mentioned terminal of the solenoid 40' and the line wire 29, by wires 46 and 41, is a normally open push-button switch 48. When switch 48 is closed, the solenoid 40' is connected directly to the line wires 29' andcausing the solenoid to be energized, and causing the alarm circuits to be activated. The switch 48 therefore corresponds to the usual fire alarm switch employed in alarm boxes. The manually settable switch may be employed to set the alarm circuit for automatic operation by the closure of any one of the thermostats 21, as in the previously-described embodiments of the invention.

While certain specific embodiments of an improved fire alarm system have been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except asdefined by the scope of the appended claim,

What is claimed is:

In a fire alarm system, an alarm box having a vertical wall, a downwardly, movable, horizontally extending manual alarm handle element mounted on said wall and projecting externally thereof, said handle element having an elevated normal position, an alarm switch in the boxedjacent said wall, means secured to said handle element and engaging said alarm switch, arranged to close the switch responsive to downward vertical movement of the handle element from said normal position, said handle element being formed with an axial bore, a vertical plunger rod of magnetic material having a horizontal arm at its topend slidably en aged. in said bore, whereby said vertical plunger rod isdetaohably connected at the upper end thereof. tosaid handle element, and a vertical solenoidv mounted in said fire box and slidably receiving said plunger rod axially therein, said solenoid being arranged to move the plunger rod downwardly responsive to energization of said solenoid, whereby to close said alarm switch.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 472,623 Lockwood Apr. 12, 1892 536,730 Mailloux Apr. 2, 1895 881,005 Kleinschmidt Mar. 3, 1908 1,058,261 Reid Apr. 8, 1913 1,483,710 Black Feb. 12, 1924 1,624,059 Miller Apr. 12, 1927 1,842,128 Strackbein Jan. 19, 1932 2,304,608 Smythe Dec. 8, 1942 2,479,621 Jackson Aug. 23, 1949 will 

